1. Field of the Invention
The present invention relates to a semiconductor memory device, and more particularly, to a semiconductor memory device and a magneto-logic circuit which vary the direction of a magnetically induced current flowing through a magnetic induction layer according to a logical combination of a plurality of input values.
2. Description of the Related Art
A magnetic random access memory (RAM) has an operating speed higher than that of a static random access memory (SRAM), integration corresponding to that of a dynamic random access memory (DRAM), and nonvolatile memory characteristic corresponding to that of a flash memory. The magnetic RAM is a memory device that senses current variations according to magnetization directions of ferromagnetic thin films formed in a multi-layer structure, and reads and writes information using the current variations. The magnetic RAM has a high operating speed, low power consumption and high integration owing to characteristics of the ferromagnetic thin films and can perform a nonvolatile memory operation of a flash memory.
Magnetic RAMs use a giant magnetoresistive (GMR) phenomenon or a spin polarization magnetic permeation phenomenon which are generated because a spin largely affects the electron transfer phenomenon. Magnetic RAMs employing GMR use a difference between resistance when spin directions of two magnetic layers are identical to each other and resistance when the spin directions are different from each other. Magnetic RAMs employing the spin polarization magnetic permeation use the phenomenon that a case where spin directions of two magnetic layers are identical to each other has current permeation better than a case where the spin directions are different from each other.